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I. Semenov1, S. V. Mirnov1, K. McGuire,
M. G. Bell, E. Fredrickson, M. Okabayashi,
P. Savrukhin2, G. Taylor, V. A. Vershkov2,
L. Zakharov
Princeton University, Plasma Physics Laboratory, Princeton,
NJ 08543, USA
1 TRINITI, Troitsk, 142092, Moscow Reg., Russia
2 RRC ``Kurchatov Institute'' 123182, Moscow, Russia
Abstract. The behaviour of MHD perturbations before and during disruptions in
the TFTR Reversed Shear (RS) plasma with
qmin 
2 was
analysed. In the
qmin region tearing modes, wave-like
modes, and mixed tearing plus wave-like modes are followed by
disruption. Sometimes a helical snake (helix) appears at the X-point of
the
qmin island. The local outward electron energy transport
near the X-point can be explained by the development of ``positive'' magnetic
islands. It is proposed that the disruption is initiated when the X-point of
the magnetic islands coincides in one toroidal position near torus equator.
IAEA 2001
